1. Field of the Invention
This invention relates generally to the art of recording optical disc masters, and more particularly to a method and apparatus for a enclosing a pregrooved, transparent optical disc in a portable container that effectively maintains a clean room environment, which is adaptable to serve as the site mounting for optical discs and optical disc masters during precision recording thereon. When the packaged disc assembly is mounted on a spindle for recording, the process of recording by laser causes effective ablating or consumption of thin optically active layers on the optical disc surfaces to form pits. The optically modified surface can then be electroformed to form a disc master.
2. Description of the Prior Art
Optical disc masters are articles from which all pre-recorded mass produced consumer optical discs are subsequently molded. Current methods of producing optical disc masters employ highly stable precision turntable apparatus operating in a cleanroom environment. One currently used method is the photoresist technique commonly used in the semiconductor industry. This method would spin coat a lamina of photoresist material upon a very thick, smooth, polished circular plate of glass. A data modulated laser is set immediately above the plate by means of a complex translational mechanism that enables the laser to move outward from the center of the glass plate while rotating the glass plate on a turntable and concomitantly radiating the surface of the material on the plate. This results in a spiral track being created in the photoresist material by the laser. Pits are created by exposure to the data modulated laser along the spiral path. This process requires that the entire equipment and operation be performed in what is typically called a cleanroom environment in which the laser path is unobstructed and the photoresist material remains pristine and uncontaminated.
Currently, there are variations in photoresist mastering techniques which employ the turntable and spiral track system described above. By using ablative surfaces rather than photoresist material on the circular glass plates, lasers can ablate the optical disc surface to cause the desired pits. However, a cleanroom environment is required for all steps in this process. The construction and maintaining of a cleanroom environment is in itself cumbersome and expensive. Also, the present art of manufacturing optical disc masters in cleanrooms is costly. There remains a need for advance beyond the prior art to a manner of mastering optical discs that is simpler and more economical.